Article formed from at least a fibrous material jet comprising at least a null thickness zone and method for making same

ABSTRACT

The present invention relates to an article formed from at least one ply of fibrous material comprising at least one region of zero thickness, characterized in that said region is covered on at least one of its faces with an at least partly transparent or translucent structure placed so as to reveal a transparent or translucent window in the paper.

The present invention relates to an article comprising a fibrous layerand an at least partially transparent or translucent structure, and alsoto the method of manufacturing said article.

The invention relates more particularly to the manufacture in general ofsecurity papers that include a transparent window.

In this regard, mention may be made of a number of examples drawn fromthe prior art possessing a similar structure but obtained using quitedifferent manufacturing methods.

In patent EP 690 939, the Applicant disclosed a security paper having atransparent window obtained by inserting a plastic film between twoplies of fibrous material.

This technique consists in embossing two strips of paper in the courseof formation, by means of raised parts integrated into the wire screenof a cylinder mold paper machine, these raised parts being high enoughto prevent the deposition of paper fibers at certain points on the paperstrip. This results in a through-hole in the paper.

Next, two fibrous layers are jointed together so as to bring the hole inone fibrous layer so as to face that in the other layer, the plasticfilm passing through the place of the superposed holes. This results ina transparent window in the paper.

However, this technique has a number of drawbacks.

One of the drawbacks is that the film sandwiched in the structure of thepaper may cause deformations of the sheet. Since the sheet is no longerflat, the paper on the one hand loses some of its attraction and, on theother hand, is not easily printable and/or stackable.

In addition, this method of forming the windows in the paper also hasthe following drawbacks:

On the embossed edges of the paper, certain defects may thus appear.Firstly, the edges are not regular and straight. Secondly, this methodof embossing the paper results in an effect that is often frequent anddifficult to avoid, namely the appearance of “barbs”, that is to sayfibers or fibrils that extend beyond the edges, resulting from the papernot being cut properly but pushed back toward the outside. A fiber thathas succeeded in withstanding the tensile force of the embossing moldconsequently remains partly caught in the fibrous structure, theremaining part extending beyond the hole thus formed.

One of the objects of the invention is therefore to eliminate thedrawbacks of the prior art as mentioned above.

Another object of the invention is therefore to form a transparentwindow in a paper based on a cellulose material by cutting or embossingits surface.

For this purpose, the Applicant proposes to no longer apply atransparent plastic film on the inside of two fibrous layers, but todeposit an at least partly transparent or translucent structure,especially a transparent plastic film, a tracing paper or a printedpatch having a transparent window, directly on the fibrous layer at theposition of the hole formed in the fibrous layer by embossing, so as toconceal the ill-formed edges of the hole by means of opaque partspresent beforehand or deposited subsequently on the applied structureand surrounding an at least partly transparent or translucent regionthereof.

Another solution envisioned by the Applicant is to form the hole in thefibrous layer by means of a cutting device downstream of the formationof the fibrous layer, so as to avoid the appearance of the “barb” effectand then to cover this hole with an at least partly transparent ortranslucent structure, it being possible for this structure to be, forexample, a transparent plastic film, a tracing paper or a printed patchthat includes a plastic window.

Consequently, the invention firstly relates to an article formed from atleast one ply of fibrous material comprising at least one region of zerothickness, characterized in that said region is covered on at least oneof its faces with an at least partly transparent or translucentstructure placed so as to reveal a transparent or translucent window inthe paper.

In this article, the aforementioned structure may be covered with anopacifying substance so as to conceal the edges of the hole formed inthe fibrous material.

This opacifying substance may be chosen from printing inks, liquidcrystals, metal particles, magnetic particles, thermochromic substancesand iridescent substances.

Specifically, the at least partly transparent or translucent structuremay be a tracing paper, a transparent plastic film or a printed patchthat includes a plastic window.

In the case of a patch, the dimensions of the latter must be larger thanthe hole formed in the fibrous material so that the edges of the holeformed in the fibrous material are concealed by the patch, the edges ofthe transparent window in the patch being placed above the empty spaceleft by the hole formed in the fibrous material.

In particular, especially in the case of application to value orsecurity papers, it is possible to apply, to the at least partlytransparent or translucent structure, in particular a plastic film, atracing paper or a patch, a security substance chosen from metalparticles, magnetic particles, thermochromic substances, iridescentsubstances, liquid crystals and mixtures thereof.

Another way of providing said article with security is also to apply adiffractive element to said at least partly transparent or translucentstructure so as to create a security hologram, which would prevent anyfraudulent copies of the article, for example by reprographictechniques.

Other devices for protection against falsification are conceivable forsaid article.

Thus, it is possible to provide a step of printing the article inquestion, once the at least partly transparent or translucent structurehas been deposited on the holed region of the fibrous layer so as toconsolidate the assembly from the document security standpoint.

The hole in the transparent window may also be used to place thickelements, having a thickness of around 100 μm up to the thickness of thearticle.

These thick elements will be placed on the at least partly transparentor translucent structure, whether on the front side or the reverse side.

Such elements may for example be printed circuits, microprocessors,electronic chips, magnetic elements, metallic elements, plasticelements, detection devices that emit a signal when they are placed in asuitable light or electromagnetic field.

In the case of electronic circuits, an antenna may be deposited at thesame time and coupled to the circuit on the at least partly translucentor transparent element.

These elements may also be thick so as to allow the document to berecognized by the blind, owing to the difference in thickness created.

Thus, a number of discrete thick particles, such as crystals, metal orplastic particles, or an object having differences in thickness, areconceivable at this point.

Although the article obtained by the present invention may be perfectlysuitable for all types of application, it is particularly intended forthe formation of bank notes, security papers in general, gift vouchers,value documents in general, coupons, labels for protecting a brand orproduct, traceability labels.

Likewise, the invention relates to the method of manufacturing saidarticle described below.

The method comprises the following steps:

-   -   formation of at least one ply of fibrous material;    -   production of a hole in the fibrous material;    -   deposition of an at least partly transparent or translucent        structure at the position of the hole on the front side and/or        on the rear side of the fibrous layer, so as to reveal a        transparent or translucent window in the article.

The structure may include at least one of the following elements: aholographic and/or diffractive element; a magnetic, metallic orcrystalline coating; liquid crystals; printing with a varnish or an ink;iridescent pigments; thermochromic and/or piezochromic pigments; atleast one reflective surface.

It may also include a plastic film, especially a polyester film.

The structure will be composed of a single layer or of at least twolayers, one of which is a carrier layer intended to be removed duringtransfer of the structure onto the sheet.

In the latter case, the carrier layer may comprise a plurality ofportions of film or of fibrous material, these portions being placed insuch a way that, after they have been transferred onto the sheet, theyare spaced apart on the surface of the sheet.

Advantageously, a structure will initially comprise at least thefollowing layers:

a carrier layer;

a release layer;

optionally, a layer of lacquer containing a resin and optionally apigment or dye;

a layer of metal, plastic or fibrous material; and

an adhesive layer.

The deposition of the at least partly transparent or translucentstructure may take place either by hot or cold transfer at the positionof the hole on the front side and/or reverse side of the fibrous layer,or by hot or cold lamination on the front side and/or reverse side ofthe fibrous layer.

The hole may be formed either by means of an embossing roller, duringthe wet phase of the fibrous layer, or by means of a mechanical cuttingor laser cutting device.

Optionally, the article may then be printed or covered with a securitysubstance chosen from metal particles, magnetic particles, thermochromicsubstances, iridescent substances, liquid crystals.

Additionally, at least one thick element is placed on the front sideand/or reverse side of the at least partly transparent or translucentstructure, the thick element being chosen from printed circuits,microprocessors, electronic chips, magnetic elements, metal elements,plastic elements, detection devices that emit a signal in the presenceof a suitable light or electromagnetic field.

The invention will be more clearly understood on reading the followingdetailed description of nonlimiting illustrative examples and onexamining the appended drawings, in which:

FIGS. 1A and 1B show schematically and in part, in a top view and incross section respectively, an article whose hole has been formed on acylinder mold by embossing;

FIGS. 2A and 2B show schematically and in part, in a top view and incross section respectively, an article whose hole has been formed bylaser cutting and covered with a transparent film;

FIGS. 3A and 3B show, schematically and in part, in a top view and incross section respectively, a covered article, the hole of which hasbeen formed on a cylinder mold by embossing and covered with atransparent plastic film printed on its front side;

FIGS. 4A and 4B show, schematically and in part, in a top view and incross section respectively, an article whose hole has been formed on acylinder mold by embossing, covered with a patch printed on its frontside and with a transparent film provided with an electronic chip on itsreverse side;

FIG. 5 is a schematic partial cross section of a structure that can beused;

FIG. 6 shows schematically an installation for producing a fibrous layerhaving holes formed by embossing;

FIG. 7 illustrates schematically the lamination of a fibrous layer to astructure;

FIG. 8 shows schematically the transfer of a structure onto a fibrouslayer; and

FIG. 9 shows, schematically and in part, a detail of FIG. 8.

FIGS. 1A and 1B show a medium (1) formed from a single fibrous ply,having a through-hole (2) in its surface, formed by means of anembossing roller during the wet forming of the sheet.

The fibrous layer (1) is produced from cellulose fibers that mayoptionally contain synthetic or artificial fibers.

It may be seen that the edges of the hole are irregular and notstraight.

Extending beyond the edges of the hole are “barbs”, fragments of fibersthat are still partly attached to the rest of the fibrous layer andisolated from the latter during embossing of the hole.

FIGS. 2A and 2B show a medium (1) formed from a single fibrous plyhaving a through-hole (2) in its surface, said hole being formed bymeans of a laser following formation of the fibrous layer.

It may be seen that the edges of the hole are straight and regular.

The rectangular shape of the hole is quite faithfully reproduced.

No “barb” can be seen with the naked eye.

Consequently, the transparent window may be easily obtained in thispaper by covering the fibrous layer at the place of the hole with atransparent plastic film 3 on the front side, as shown in FIGS. 2A and2B.

FIGS. 3A and 3B show one particular configuration of the invention, inwhich the single-ply fibrous layer (1) has been holed by embossing, withthe appearance of “barbs”.

The front side of the fibrous layer is covered with a transparentplastic film (3).

Said film is then covered with an opacifying substance (4) which, here,is composed of ink over a region surrounding the hole so as, on the onehand, to conceal the barbs and, on the other hand, to leave atransparent region on the inside of the covered hole.

FIGS. 4A and 4B show a variant of the invention which a transparent film(3) is applied to the reverse side and an opaque patch (5) is applied tothe front side so as to cover the hole, the patch having, however, acut-out in the middle of it.

The region covered by the cut-out in the patch is placed so as again toconceal the “barbs” of the fibrous layer.

Since the transparent film itself bears an electronic chip (6) on itssurface, it is necessary to place the chip in an adjusted manner insidethe hole so as to avoid an overthickness in the article.

In the previous examples, the film (3) consists only of a single layerof transparent plastic, for example polyester.

It would not be outside the scope of the invention to use a differentstructure, especially a multilayer structure.

To give an example, FIG. 5 shows a composite structure (3′) comprising:

-   -   a polyester carrier layer (10);    -   a release layer (11), for example made of wax;    -   a lacquer layer (12) containing a resin and optionally a pigment        or dye;    -   a metal layer (13), for example an aluminum layer;    -   an adhesive layer (14) for fastening an element (6) to the        fibrous layer (1)—the adhesive layer (14) may be based on a        hot-melt resin.

In the example described, the carrier layer (10) has a thickness ofabout 12 μm and the accumulative thickness of the layers (11) to (14) isabout 2 to 3 μm.

The layers (12), (13) and (14) form a film (3″) to be transferred ontothe sheet (1).

The structure (3′) is also called a “foil” and it allows the film (3″)to be joined to the sheet (1), for example by hot pressing, during whichoperation the release layer (11) melts and allows the carrier layer (10)to be separated from the other layers. The heat provided during thisoperation also activates the adhesive layer (14) so as to thermally bondthe film (3″) to the sheet (1).

The metal layer (13), for example made of aluminum, may have a surfaceappearance that it makes it possible to reflect light through thecolored lacquer layer (12), thus creating a color effect on the surfaceof the article.

The layer (12) may have a hologram consisting of a diffraction grating.The latter may be produced by means of a matrix of a transfer machineallowing the film (3″) to be transferred onto the sheet (1). As avariant, the hologram may be produced before the layer (12) is assembledwith the other layers.

The metal layer (13) may be replaced with a plastic layer.

The film (3) or (3″) may or may not entirely cover one side of thearticle.

The film (3) or (3″) may or may not extend continuously between twoopposed edges of the article.

The film (3) or (3″) may form a patch on the article.

A method for producing a fibrous layer comprising at least onethrough-hole will now be described with reference to FIG. 6.

FIG. 6 shows, in part and schematically, two cylinder mold papermachines (35) and (36).

The first machine (35) includes a vat (37) containing a suspension offibers, for example cellulose fibers, in which a rotating wire cylinder(38) is partly immersed, said cylinder defining a surface (39) incontact with which a paper ply (40) is continuously formed and pulledoff by a pick-up felt (42). The surface (39) includes relief embossingso as to create through-holes in the first ply (40).

The second machine (36) includes, like the machine (35), a vat (37), arotating wire cylinder (44) defining a surface (47) in contact withwhich a second paper ply is formed.

The surface (47) of the wire cylinder (44) includes relief embossing soas to create holes (46) in the second ply, the holes (46) being placedso as to be superposed with the holes (45) in the first ply duringassembly of the two plies, the assembly taking place as the two pliespass between the cylinder mold (44) and a rotating roll (48).

Such an installation is in particular described in greater detail inEuropean patent EP 0 687 324.

The sheet can be subsequently cut up to the format of the article to beproduced.

Again the cavity may be produced by other means, for example using alaser or mechanical abrasion.

The film and the sheet may be joined together in many ways withoutdeparting from the scope of the invention.

FIG. 7 shows schematically the lamination assembly of a film (3) to afibrous layer (1) by passage between two rotating rolls (50) and (51).In this figure, the film (3) is brought beforehand into contact with asize press (53).

The film (3) and the sheet (1) may therefore be positioned, one withrespect to the other by registration, in such a way that an opaque parton the film covers the edges of the cavity formed in the sheet (1). Inthe example in question, the film (3) remains permanently on the sheet(1).

In the case of the composite structure (3′), the film (12),(13),(14) maybe transferred, for example by hot transfer, onto the sheet (1), asillustrated in FIGS. 7 and 8.

In such a transfer method, the sheet (1) and the structure (3′) may bedriven with the carrier layer (10),(11) so as to move in the samedirection by means of a machine comprising a first rotating cylindercarrying dies (56) and a second rotating cylinder (57). The film(12),(13),(14) and the sheet (1) may be joined together as they passbetween the cylinders (55) and (57). In FIG. 8, it may be seen that,after they pass between the rotating cylinders (54) and (57), thecarrier layer and the release layer are separated from the other layers(12),(13) and (14) that are transferred onto the sheet (1).

The film (12),(13),(14) may also be brought between a die (56) and thesheet (1) in a direction generally transverse to the movement of thesheet, as described in European patent EP 0 473 635.

Of course, the invention is not limited to the illustrative examplesthat have just been described.

Each through-cavity may be closed on one side only by a film, or on bothsides by two films.

Each through-cavity may also be closed on one side by a film and on theother side by a fibrous layer.

In particular when an element is placed in the cavity of the sheet bytransfer, the layer of the structure bearing the element may be based onfibrous material.

1. An article comprising fibrous material, wherein said fibrous materialis in the form of (i) a single ply comprising fibers or (ii) a laminatecomprising at least two plies, each of said two plies comprising fibers,wherein said fibrous material comprises at least one region of zerothickness forming a window in the fibrous material, wherein edges ofsaid window are covered on at least one outside face of said fibrousmaterial with an at least partly transparent or translucent structureplaced so as to reveal the window in the fibrous material, wherein atleast a portion of the structure is covered with an opacifying substanceso as to conceal the edges of the window formed in the fibrous material,wherein at least a portion of the window is not covered by theopacifying substance.
 2. The article as claimed in claim 1, wherein theopacifying substance is chosen from printing inks, liquid crystals,metal particles, magnetic particles, thermochromic substances andiridescent substances.
 3. The article as claimed in claim 1, wherein thestructure is a transparent plastic film.
 4. The article as claimed inclaim 1, wherein the structure is a tracing paper.
 5. The article asclaimed in claim 1, wherein the structure is a printed patch thatincludes a cut-out.
 6. The article as claimed in claim 5, wherein thepatch has larger dimensions than the hole formed in the fibrous materialso that the edges of the hole formed in the fibrous material areconcealed by the patch, the edges of the cut-out in the patch beingplaced above the empty space left by the hole formed in the fibrousmaterial.
 7. The article as claimed in claim 6, wherein the patch iscovered with a security substance chosen from metal particles, magneticparticles, thermochromic substances, iridescent substances, liquidcrystals and mixtures thereof.
 8. The article as claimed in claim 1,wherein the at least partly transparent or translucent structure definesa security hologram.
 9. The article as claimed in claim 1, wherein itdefines an article chosen from a bank note, a security paper, a giftvoucher, a value document, a coupon, a label for protecting a brand orproduct, and a traceability label.
 10. The article as claimed in claim1, wherein said fibrous material is in the form of a single plycomprising fibers.
 11. The article as claimed in claim 1, wherein saidfibrous material is in the form of a laminate comprising at least twoplies, each of said two plies comprising fibers.